In 1964, after the 1250-kg jet-powered car Spirit of America lost its parachute
ID: 1280344 • Letter: I
Question
In 1964, after the 1250-kg jet-powered car Spirit of America lost its parachute and went out of control during a run at Bonneville Salt Flats, Utah, it left skid marks about 8 km long. (This earned a place in the Guinness Book of World Records for longest skid marks.)
1) a) If the car was moving initially at a speed of 843 km/h, and was still going at 250 km/h when it crashed into a brine pond at the end of the skid marks, find the coefficient of kinetic friction ? k.?
2) b) What was the kinetic energy of the car 39 s after the skid began?
Explanation / Answer
a) v^2 = v0^2 + 2 a x
(250.0E3/(60*60))^2 = (843.0E3/(60*60))^2 + 2*a*8.0E3
a=-3.13 m/s^2
friction = m a
u m g = m a
u = a/g =3.13/9.81 = 0.32
b)
v = v0 + a t = 843.0E3/(60*60) - 3.13*39= 112 m/s
KE = 1/2 mv^2 = 0.5*1250*112^2= 7.84E6 J